You should be able to just slide the serving and peep down or up the string (depending on how tight the serving is). Just hold it tight and force it the way you want to go. If you are using a peep that is held on with two budles of string, the peep is going to rotate as you manuver it up or down. Make the move needed to have the open eye = on the money effect and then deal with the peeps rotation afterwards. That's another ball of wax.

If your peep is held into position with 3 or 4 bundles of string then you should be OK, Make the move and you will find out. (you can always move it back)